Photographic development process

ABSTRACT

A PHOTOGRAPHIC LIGHT-SENSITIVE MATERIAL COMPRISING A SILVER HALIDE EMULSION LAYER CONTAINING A COMPOUND CORRESPONDING TO ONE OF THE FOLLOWING STRUCTURAL FORMULAE IA OR IB:   2-A1,2-Z1,4-A2,4-Z2,6-A3,6-Z3-1,3,5,2,4,6-   TRIAZATRIPHOSPHORINE OR   2-A1,2-Z1,4-A2,4-Z2,6-A3,6-Z3,8-A4,8-Z4-1,3,5,7,2,4,6,8-   TETRAZATETRAPHOSPHOCINE   WHEREIN:   EACH OF A1, A2, A3, A4, Z1, Z2, Z3, AND Z4 STANDS FOR A CHLORINE ATOM OR A POLYOXYALKYLENE GROUP OF THE FORMULA -(OR1)N-X, AT LEAST ONE OF THE GROUPS A1, A2, A3, A4, Z1, Z2, Z3, OR Z4 BEING THE GROUP -(OR1)N-X WHEREIN N REPRESENTS AN INTEGER OF AT LEAST 5, THE   -(OR1)-   GROUP REPRESENTING REPEATING UNITS ENTIRELY CONSISTING OF ETHYLENE OXIDE UNITS OR A MIXTURE OF ETHYLENE OXIDE UNITS AND PROPYLENE OXIDE UNITS, AND X BEING A TERMINAL GROUP THAT IS UNREACTIVE WITH RESPECT TO AN ACTIVE HALOGEN ATOM OF AN ACID HALIDE COMPOUND AND IS SELECTED FROM THE GROUP CONSISTING OF   -O-R, -OOC-R, -S-R, OR -N(-R)2   WHEREIN R IS AN ALKYL, AN ARYL, A CYCLOALKYL, OR A HETEROCYCLIC RADICAL, SAID RADICALS BEING UNREACTIVE WITH RESPECT TO SAID ACTIVE HALOGEN ATOM IS DESCRIBED. THE SILVER HALIDE EMULSION HAS A HIGH DEVELOPING ACTIVATION IN COMBINATION WITH A VERY LOW FOG PRODUCTION.

United States atent 3,552,968 PHOTOGRAPHIC DEVELOPMENT PROCESS Jozef Frans Willems, Wilrijk, Belgium, assignor to Gevaert-Agfa N.V., Mortsel, Belgium, a Belgian comp y No Drawing. Filed July 5, 1967, Ser. No. 651,136 Claims priority, application Great Britain, Aug. 19, 1966, 37,178/ 66 Int. Cl. G03c /30, 1/48, 1/02 US. Cl. 96-663 5 Claims ABSTRACT OF THE DISCLOSURE A photographic light-sensitive material comprising a silver halide emulsion layer containing a compound corresponding to one of the following structural Formulae Ia or Ib:

wherein each of A A A A Z Z Z and Z stands for a chlorine atom or a polyoxyalkylene group of the formula --(OR ),,X, at least one of the groups A A A A Z Z Z or Z, being the group --(OR ),,X wherein n represents an integer of at least 5, the

wherein R is an alkyl, an aryl, a cycloalkyl, or a heterocyclic radical, said radicals being unreactive with respect to said active halogen atom is described. The silver halide emulsion has a high developing activation in combination with a very low fog production.

This invention relates to an improved photographic material and more especially to silverhalide emulsion layers having a better developability and an increased general light-sensivity.

It is known to further increase the general sensitivity of photographic emulsions, which have already obtained an optimal sensitivity with the so-called chemical sensitizers, e.g.,the sulphur sensitizers, by adding polyglycols to the photographic elements (see British patent specifications 548,019 and 600,058).

It is also known that such an additional increase of sensitivity may be obtained when incorporating into the photographic material alkylene oxide polymers prepared by the polymerization of alkylene oxide in the presence of dehydration products of hexitol rings, aliphatic alcohols, aliphatic acids, amines, amides and phenols (see British patent specifications 592,676, 748,745 and 748,750).

Further, it is known that these polyglycols and alkylene oxide polymers must have a molecular weight of at least 400 and that it is practically necessary to use compounds having a molecular weight from 1,500 to 2,000 and more to obtain a substantial eifect.

Contrarily to the other known methods to increase the sensitivity of silver halide emulsions, e.g. the methods according to which the inherent sensitivity is increased by chemical sensitizers, and the methods according to which the spectral absorption is increased by cyanine dyestuffs, it has been observed that the final sensitivity of the silver halide emulsion layers containing the above described compounds is higher, since these compounds have a favorable influence upon the development of these silver halide emulsion layers in the conventional developers. Thus these compounds may be considered as developing accelerators.

However, it is also known, that these compounds may be used as ingredients in more sensitive silver halide emulsion layers, but they impair the keeping quality of these layers, particularly at high temperatures and elevated degrees of relative humidity, since they induce a substantial increase of fog. It has been also observed that the incorporation of these compounds into the photographic material in order to prepare more sensitive silver halide emulsion layers impaired the image tone of the developed silver, thereby forming brown and red-brown images.

These disadvantages can be reduced, even practically oxyacid of phosphorus. For such type of condensation products containing in their structure ester groups of an oxyacid of phosphorus. For each type of condensation products reference is made to the United Kingdom patent specifications 945,340 and 1,015,023, the German patent specification 1,182,523 and the French patent specification 1,396,860.

It has now been found that a high developing activation in combination with a very low fog production can be obtained by the use in working contact with a light-sensitive silver halide emulsion layer of a cyclic phosphonitrile trimer or tetramer derivative wherein at least one of the phosphorus atoms is linked to a polyoxyalkylene oxide chain forming part of a terminally monoblocked polyoxyalkylene oxide polymer or a cyclic phosphonitrile trimer or tetramer derivative wherein trimer and/or tetramer phosphonitrile nuclei are linked together through their phosphorus atoms by means of a bivalent radical containing oxyalkylene units.

Preferred representatives of the first type of phosphonitrile trimer and tetramer derivatives fall within the scope of the following structural Formulae la and Ih wherein each of A A A and A represents a chlorine atom at least one of them, however, being a polyoxyal'kylene residue of the formula -('OR ),,X, wherein 11 rep resents a positive integer of at least 5, preferably from 5 to 35, and the (O'R repeating units are entirely consisting of ethylene oxide units or consisting of a mixture of ethylene oxide and propylene oxide units, the ratio of said units being preferably chosen in such a way that water-soluble products are obtained, and X represents a terminal group that is unreactive in respect of an active halogen atom of an acid halide compound e.g.

wherein R represents an alkyl, aryl, cycloalkyl or heterocyclic radical, including said radicals substituted with groups that are unreactive in respect of said halogen atom; and

each of Z Z Z and Z represents a chlorine atom or a radical as described for A the (OR )units are entirely consisting of ethylene oxide units or of a mixture of ethylene oxide and propylene oxide units, the ratio of said units being preferably chosen in such a way that water-soluble products are obtained;

R represents an alkyl radical or an aralkyl radical,

X- represents an acid radical, and

n is an integer of at least 5, preferably between 5 and 35.

wherein:

Specific polyoxyalkylene diols according to the general formulae above are mentioned, erg. in the United Kingdom patent specification 1,015,023 and French patent specification 1,447,262. Some of these diols are commercially available, for example under the trade name Pluronic L 31, which is a water soluble mixed-condensation product of ethylene oxide and propylene oxide, with an average molecular weight of 1,100, manufactured by Wyandotte Chemicals Corporation, Wyandotte, Mich., U.S.A.

The condensation reaction is preferably carried out in an inert solvent for the reaction compounds, e.g. benzene or dioxane and in the presence of a basic compound, e.g. piperidine, triethylamine, sodium metal and the like. The chloride salts formed during the condensation reaction with said basic compound are filtered off at the end of the reaction and the formed phosphonitrilepolyoxyalkylene derivative separated by evaporating the solvent.

Although it is possible, depending upon whether a phosphonitrile chloride trimer or tetramer is used, to introduce six or eight polyoxyalkylene residues or repeating units, the reaction conditions are rather severe and in order to avoid the application of a rather long reaction time and too high reaction temperatures it is desirable that only half of the chlorine atoms are substituted by the radicals containing oxyalkylene units. Moreover, it has been found that condensation compounds that still contain chlorine atoms produce less fog on storage of the photographic silver halide emulsion layers.

When applying mild reaction conditions as illustrated 4 hereinafter the reaction between phosphonitrile chloride trimer or tetramer and an excess of polyethylene glycol can result in a condensation product having unit with either three or four chlorine atoms respectively.

The following preparations illustrate the production of compounds suitable for use according to the present invention.

PREPARATION 1 .Reaction of monomethoxy-polyethylene glycol (average molecular weight 750) with phosphonitrile dichloride (trimer).

To a solution of 225 g. (0.3 mole) of methoxypolyethylene glycol (average molecular weight 750) in 400 ccs. of benzene are added at room temperature: a solution of 34.8 g. (0.1 mole) of phosphonitrile dichloride (trimer) in 200 ccs. of benzene and a solution 30.3 g. (0.3 mole) of triethylamine in 100 ccs. of benzene. This mixture is stored at room temperature for 24 days. After this storing period 39 g. of triethylamminoum chloride are formed. The precipitate of triethylammonium chloride is filtered by suction and the benzene filtrate is concentrated by evaporation. The condensation product obtained is water-soluble. Yield: 253 g.

PREPARATION 2 Reaction of the condensation product of 20 moles of ethylene oxide and 1 mole of cetyl alcohol with phosphonitrile dichloride (trimer).

To a solution of 168.3 g. (0.15 mole) of the condensation product of 20 moles of ethylene oxide and 1 mole of cetyl alcohol in 400 ccs. of benzene are added at room temperature: a solution of 17.4 g. (0.05 mole) of phosphonitrile dichloride (trimer) in 100 ccs. of benzene and a solution of 15.15 g. (0.15 mole) of triethylamine in 100 ccs. of benzene. This mixture is stored for 21 days at room temperature. After this storing period 19.3 g. of triethylammonium chloride have formed. The precipitate consisting of the said chloride is filtered by suction and the benzene filtrate is concentrated by evaporation. The condensation product obtained is water-soluble. Yield: 178 g.

PREPARATION 3 Reaction of a water-soluble mixed condensation product of ethylene oxide and propylene oxide (average molecular weight 1,100) with phosphonitrile dichloride (trimer).

To a solution of 79 g. (0.075 mole) of the said mixed condensation product in 300 ccs. of benzene are added at room temperature: a solution of 17.4 g. (0.05 mole) of phosphonitrile dichloride (trimer) in 100 ccs. of benzene and a solution of 15.15 g. (0.15 mole) of triethylamine in ccs. of benzene. This mixture is stored for 21 days at room temperature. After this storing period 19.5 g. of triethylammonium chloride have formed. The precipitate of triethylammonium chloride is filtered by suction and the benzene filtrate is concentrated by evaporation. The condensation product obtained is soluble in water/ethanol (80/20). Yield: g.

PREPARATION 4 Condensation product of polyethylene glycol (average molecular weight: 1,000) with phosphonitrile dichloride (trimer).

To a solution of g. (0.15 mole) of polyethylene glycol (average molecular weight: 1,000) in 500 ccs. of benzene are added at room temperature: a solution of 34.8 g. (0.1 mole) of phosphonitrile dichloride (trimer) in 200 ccs. benzene and a solution of 30.3 g. (0.3 mole) of triethylamine in 75 ccs. of benzene. This mixture is stored for 25 days at room temperature. After this storing period 39 g. of triethylammonium chloride have formed. The precipitate consisting of the said chloride is filtered by suction and the benzene filtrate is concentrated by evaporation. The condensation product obtained is soluble in water. Yield: 168 g.

PREPARATION Condensation product of polyethylene glycol (average molecular weight: 2,000) with phosphonitrile dichloride (trimer).

To a solution of 150 g. (0.075 mole) of polyethylene glycol (average molecular weight: 2,000) in 600 ccs. of benzene are added at room temperature: a solution of 17.4 g. (0.05 mole) of phosphonitrile dichloride (trimer) in 100 ccs. of benzene and a solution of 15.15 g. (0.15 mole) of tn'ethylamine in 75 cos. of benzene. This mixture is stored for 27 days at room temperature. After this storing period 19 g. of triethylammonium chloride have formed. The precipitate consisting of the said chloride is filtered by suction and the benzene filtrate is concentrated by evaporation. The condensation product obtained is soluble in water. Yield: 157 g.

PREPARATION 6 Condensation product of polyethylene glycol (average molecular weight: 1,000) with phosphonitrile dichloride (tetramer).

T o a solution of 50 g. (0.05 mole) of polyethylene glycol (average molecular weight: 1,000) in 170 ccs. of benzene are added at room temperature: a solution of 11.6 g. (0.025 mole) of phosphonitrile dichloride (tetramer) in 70 ccs. of benzene and a solution of 10.1 g. (0.1 mole) of triethylamine in 40 ccs. of benzene. The solution is stored for 27 days at room temperature. After this storing period 13 g. of triethylammonium chloride have formed. The precipitate consisting of said chloride is filtered by suction and the benzene filtrate is concentrated by evaporation. The condensation product obtained is soluble in water. Yield: 57 g.

When saying that the new compounds according to the present invention are used in working contact with the silver halide emulsion layer it is meant that they must be present during the development in the emulsion layer and this is realized either by incorporating them therein before exposure or by diffusion from an adjacent water-permeable layer or developing composition.

Preferably, the developing activators used in the present invention are added directly to the silver halide emulsion. However, they may be also added to a hydrophilic colloid layer adjacent to said emulsion layer. The addition of these compounds may be eventually effected in the form of an aqueous solution or of a mixture of Water and an organic solvent which does not impair the photographic properties of the light-sensitive material.

The emulsion layer may occasionally by treated with a solution of the development activators instead of incorporating said solution into the emulsion ready for coating.

The developing activators used in the present invention may be incorporated at different steps of the emulsion preparation. For instance they may be added as a separate addition or in admixture with one or several other ingredients used for the initial precipitation of the silver halide grains, during the physical or chemical ripening process or in any other step before coating the emulsion. However, they are preferably added to the emulsion after its chemical ripening and just before coating.

The optimum amount added to the emulsion depends upon the selected compound, the nature of the colloidal binding agent for the silver halide present in the emulsion. Generally, the developing activators used in the present invention are added in an amount of 30 mg. to 6 g. per mole of silver halide.

In order to increase the light-sensitivity of a silver halide emulsion layer of a photographic material the developing activators used in the present invention can be incorporated in the silver halide emulsion layer in combination with small amounts of a sulphur containing compound, such as allyl isothiocyanate, allyl thiourea and sodium thiosulphate, small amounts of reduction sensitizers, such as the tin compounds described in the Belgian patent specifications 493,464 and 568,687 and the iminoaminomethane sulphinic acid compounds described in the British patent specification 789,823, or small amounts of precious metal compounds, such as of gold, platinum, palladium, iridium, ruthenium and rhodium. Of course, the sensitizing effect of the compounds initially present in the gelatin may be very advantageously completed by the new developing activators.

In combination with the developing activators used in the present invention, stabilizers may also be used, e.g. mercury compounds, and the compounds mentioned in the prior art and claimed in the Belgian patent specifications 571,916 and 571,917, and compounds of the oxytriazolopyrimidine type, e.g. S-methyl -'7 hydroxy-s-triazolo-[1,5-a]-pyrimidine.

It is also usual to sensitize and/or to stabilize silver halide emulsions by incorporating cadmium salts or by processing these emulsions in the presence of cadmium salts. Other compounds, which sensitize the photographic emulsion by development acceleration, such as organic onium compounds and polyonium compounds, preferably of the ammonium or sulphonium type, e.g. quaternary tetraalkylammonium salts, alkylpyridinium salts, bis-alkylene pyridinium salts, alkylquinolinium salts, and trialkylsulphonium salts can be used together with the development accelerators according to the invention in the developing solution as well as in the light-sensitive material. Further, other ingredients such as fog inhibiting agents, colour couplers, developng substances, hardeners and wetting agents, may also be added in a known manner to the emulsion, without impairing it in any way.

Owing to their property of promoting the developability, the new compounds may be very efficiently used to increase the X-ray sensitivity and the general lightsensitivity of orthochromatic, panchromatic and all special emulsions as well as the conventional non-spectral sensitized emulsions. They may be added separately or in combination with optically sensitizing dyestuffs. In the latter case, the addition must be effected before or after the addition of the optically sensitizing dyestuffs. In addition, they may be very advantageously used in the most various emulsions since they lead to an outstanding sensitivity increase in the negative as well as in the positive emulsion types.

The new compounds can be applied, with particularly good results, for the development of light-sensitive materials suitable for use in the graphic art, on account of the very contrasting development obtained when these compounds are added either to the formaldehyde bisulphitehydroquinone developer or to the light-sensitive emulsion layer. Further, it has been found that in the latter lightsensitive materials these compounds improve the quality of the developed dot screen prints (dot sharpness) and reduce the number of peppers.

When using the development accelerating compounds in the developing bath they are normally incorporated therein in amounts ranging from 0.1 g. to 10 g. per liter. If necessary, these compounds can also be added in amounts exceeding that range. Preferably they are used in the photographic material as well as in the developing bath in water-soluble form.

The following examples illustrate the present invention without, however, limiting it thereto.

Example 1 A washed negative gelatin silver bromoiodide emulsion (average grain size of the silver halide: 0.8 the silver halide of which consists of 94.5 mole percent of silver bromide and 5.5 mole percent silver iodide, is ripened at 45 C. The emulsion ready for coating contains per kg.

50 g. of silver halide, 75 g. of gelatin, 30 mg. of optical sensitizer with the following structural formula:

50 mg, of 5-methyl-7-hydroxy-s-triazolo[l,5-a]pyrimidine as a stabilizer, and 500 mg. of saponine as a wetting agent.

This emulsion is divided into several aliquot portions and to the separate portions is added one of the development accelerators as mentioned in the following Table I. The control emulsion and the emulsion portions containing a development accelerator are separately applied to a cellulose triacetate support and dried. All test strips are then exposed in the same conditions through a grey wedge and developed for 7 min. at 20 C. in a fine-grain developer of the following composition:

Water-8 ccs. Monomethyl-p-aminophenol sulphate-2 g. Hyd-roquinone-S g.

Anhydrous sodium sulphite-100 g. Borax l0 g.

Boric acid g.

Potassium bromide0.5 g.

Water to---l0()0 ccs.

The speed is represented by exposure values. A decrease in exposure value of 30 means a doubling in sensitivity.

TABLE 1 Amount of compound sensitometric results per kg. of Added compound emulsion Fog Gamma Speed 0.10 0. 60 105 Monomethoxypolyethylene glycol {300 mg 0. 09 0. 64 74 with average mol. weight of 750. 1 g... O. 12 0. 67 78 Compound of preparation 1 2 Condensation product of mole 0 76 68 of ethylene oxide and 1 mole of 75 70 cetyl alcohol. g Compound of preparation 2 8' g: g? Mixture condensation product of ethylene oxide (80 moles percent) and propylene oxide (20 300 mg 0.09 0.65 78 moles percent) (average mol. 1 g 0. 09 0. 53 83 weight of the condensation product-1,100). 0 4 Compound Preparation 3 --{iffi::::: 8:32 0:32 33 Example 2 An emulsion as described in Example 1 is used, which emulsion, however, is divided in aliquot portions and respectively added thereto the compounds mentioned in Table II. The test strips, after an incubation of 36 hours in an atmosphere of 57 C. and 34% relative humidity and after havingbeen exposed, were developed for 5 min. at 20 C. in a developer of the following composition:

Water800 ccs. Monomethyl-p-aminophenol sulphate-2 g. Hydroquinone-5 g.

Anhydrous sodium sulphite g. Crystalline sodium carbonate-40 g. Potassium bromide1 g.

Water to1 litre.

In Table II, the obtained fog values are listed.

TABLE II Amount of compound added per kg. of

Compound added emulsion Methoxypolyethylene glycol with average molecular Weight of 750.

Compound of preparation 1 g Condensation product of 20 moles of ethylene oxide and 1 mole of cetyl alcohol. 1

Compound of preparation 2.

g Mixture condensation product of ethylene oxide and propylene oxide (average mol. weight of 1100).

Compound of preparation Example 3 After the addition of the hereafter indicated amounts of developing accelerators to the silver halide emulsion as described in Example 1 and a processing identical to that of Example 1, the following sensitometric results are obtained:

TABLE III Amount of compound sensitometric results per kg. of Compound added emulsion, g. Fog Gamma Speed 0. 08 0. 49 148 Compound of preparation 4 1 0. 10 0. 57 112 Compound of preparation 5- 1 0. 10 0.61

Example 4 The following sensitometric results are obtained as described in Example 1, but after having developed the samples for 7 minutes at 20 C., in a solution having the following composition:

Monomethyl-p-aminophenol sulphate-45 g. Sodium sulphite (anhydrous)90 g.

Sodium chloride-30 g.

Boric acid till pH 7.8

Water to1000 ccs.

TABLE IV Amount of compound sensitometric results per kg. of Compound added emulsion, g. Fog Gamma Speed 0. 08 0.31 181 Compound of preparation 4. 1 O. 12 0. 41 132 Compound of preparation 5- 1 0. 11 O. 41

What we claim is:

1. A photographic light-sensitive material which comprises a silver halide emulsion layer containing a compound corresponding to one of the following structural Formulae Ia or Ib:

9 that is unreactive with respect to an active halogen atom of an acid halide compound and is selected from the group consisting of wherein:

R is an alkyl, an aryl, a cycloalkyl or a heterocyclic radical, said radicals being unreactive with respect to said active halogen atom.

2. A photographic light-sensitive material according to claim 1 wherein said compound is incorporated in the silver halide emulsion layer in an amount of 30 mg. to 6 g. per mole of silver halide.

3. A process for producing photographic images comprising the steps of image-wise exposing a photographic material containing a light-sensitive silver halide emulsion layer to electromagnetic radiation creating a latent silver image and developing said image by selectively reducing the silver halide to metallic silver in the presence of a development accelerating compound corresponding to one of the following structural Formula Ia or Ib:

wherein:

each of A A A A Z Z Z and Z stands for a chlorine atom or a polyoxyalkylene group of the formula -(OR ),,X, at least one of the groups A1, A2, A3, A4, Z1, Z2, Z3, or Z4 bCil'lg the group (OR X wherein n represents an integer of 10 from about 5 to 35, the -(OR group representing repeating units entirely consisting of ethylene oxide units or a mixture of ethylene oxide units and propylene oxide units, and X being a terminal group that is unreactive in respect of an active halogen atom of an acid halide compound and is selected from the group consisting of R -OR, OCR, SR, or -N wherein:

R is an alkyl, an aryl, a cycloalkyl or a heterocyclic radical, said radicals being unreactive with respect to said active halogen atom.

4. A process according to claim 3 wherein the development accelerator is present in the photographic material before its exposure and comes in elfective contact with the silver halide during the development.

5. A process according to claim 3 wherein the development accelerator is present in the developing solution.

References Cited UNITED STATES PATENTS 3,131,207 4/1964 Ratz 260-927N 3,346,386 "10/1967 Muller et al 9666.3 3,382,211 5/1968 B ezman et al. 260927NX 3,419,504 12/1968 Klender 260-927NX OTHER REFERENCES Matuszko, A. J., et al.: Reactions of Alkanediols with Triphosphonitrilic Chloride, Pub. in J. Org. Chem., vol. 31, No. 6, June 1966, pp. 2004 and 2005.

DAVID KLEIN, Primary Examiner U.S. c1. X.R. 9676, 

